I would like to draw a horizontal line in graphs to indicate a limit, or have some similar indicator to see immediately when a pre-defined limit is breached.
How can I achieve this?
This article applies as of PRTG 25
Set Limit Markers in Graphs
Graphs in PRTG will automatically display limits you set in the sensor channel settings. You can set upper/lower error and/or warning limits. Limits will automatically set a sensor into Warning and/or Down status. Each limit is automatically shown as a yellow or red area in a sensor graph if you configure the graph to show one sensor channel only.
| Sensor Channel Limit | Color of Area in Graph |
|---|---|
| Upper Error Limit | red |
| Upper Warning Limit | yellow |
| Lower Warning Limit | yellow |
| Lower Error Limit | red |
For example, a traffic graph with limits can look like the following:
Configuration Step-by-Step
In order to create a graph display like this, please ensure the following:
- In the sensor channel settings, in the Display section, set the option Hide from graphs for all sensor channels except for one—the one you want to have a graph with limits for.
- For the remaining sensor channel, in the Limits section, Enable Limits and set error and/or warning limits. Save your settings.
- Return to the sensor’s Overview tab to check the graph display. In order to get a filled graph, set the remaining sensor channel as Primary channel for this sensor. All other sensor channels will be displayed as a line only.
Additional information:
- If only one channel has limits, disable the other channels in the graph to see the limit markers on the graph.
- To see the error and/or warning limits on the vertical axis of the graph for a sensor that has only one channel, assign a value that is at least equal to or higher than the maximum error and/or warning limit, to the vertical axis in the Edit Channel window of the sensor.
Other alternative(s):
For "visual markers" only (a limit which doesn't affect the sensor's status) you can use a Sensor Factory Sensor.
